1. Field of the Invention
The present invention relates to "scupper drains" which are drain structures used to remove water from flat or nearly flat roofs of the kind that are constructed by applying any variety of roofing substrates over a base comprised typically of wood or concrete.
2. Description of Related Art
There are numerous varieties of flat roofs that require scupper drains. Scupper drains are often used, for example, with flat layered roofs comprised of a support base made from wood framing and plywood sheets and a substrate made from one or more layers of "roofing felt" and tar.
One or more scupper drains are located at strategic places on the roof so that water, flowing into the drain, can be removed from the, roof through appropriate plumbing. Most community building codes requires a primary drain and a secondary drain. The primary drain is generally flush with the roofing substrate so that, subject to inherent drainage rate limitations, water drains immediately from the roof through the primary drain. The overflow drain generally serves as a backup in case the primary drain becomes clogged or is otherwise unable to remove the water as quickly as it accumulates on the roof. Although it is not necessary, commercial scupper drains often include a primary drain and an overflow drain in one structure.
The community building codes ordinarily specify a required "flood level", often two inches (2"), at which point water should also begin to flow into the overflow drain. Accordingly, the top of the overflow drain must be installed at a specified height above the roofing substrate. The required flood level must be achieved during construction of a new roof and also during the repair or reconstruction of an existing roof. Maintaining the required flood level is often troublesome when repairing an existing roof because the contractor sometimes installs and sometimes removes layers of roofing substrate.
An exemplary scupper drain is described and disclosed in U.S. Pat. No. 3,884,809 which issued to the present inventor on May 20, 1975. The contents of the U.S. Pat. No. 3,884,809 are hereby incorporated and made a part of this disclosure as if fully set forth herein.
It is of course important to prevent water from leaking into or through the roof. This is especially true since such leakage can cause a catastrophic failure of the entire structure. A common leakage point is the interface between the roof drains and the layers of roofing substrate. This kind of leakage is an especially critical problem in communities that experience severe temperature changes. The leak occurs because the roofing layers expand and contract around the drain. Over time, the roofing layers may literally lift away from the support base around the drain, forming a gap. As a result, water that would ordinarily flow through the drain may instead flow into the gap between the support base and the roofing layers.
Another problem with known roof drains is lack of versatility. In particular, because the contractor may stock or be required to use different size drain pipes, the manufacture must make and the roofing contractor must buy, and often stock at great expense, different sized roof drains and different-sized components. The result is more components and additional cost to all concerned.
Some size versatility was provided by the "stepped" drain ports like those shown in U.S. Pat. No. 3,884,809. However, no known prior art roof drain provides size versatility with respect to different sized drain pipes and related drain components such as clamp rings and grates.